摘要： We reported a novel type of wavelength-tunable single-frequency ytterbium-doped fiber laser based on a double-circulator compound cavity and a section of unpumped ytterbium-doped fiber. The multi-longitudinal-mode oscillations are suppressed by the double-circulator structure and the single frequency operation is obtained finally by the standing wave grating in the unpumped ytterbium-doped fiber. The central wavelength of the laser beam is selected by a tunable filter ranging from 1040 nm to 1080 nm. The results show that the side mode suppression ratio in this range is greater than 47 dB and the maximum value is 58 dB at 1070.06 nm. The observed maximum wavelength fluctuation and power variation at 1060 nm are 0.012 nm and 0.22 dB during 1 h, respectively. The mean value of the linewidth in this range is 2.82 kHz and the minimum value of the linewidth at 1060 nm is 2.38 kHz. The relaxation oscillation frequency is right on 94 kHz.